Plotting instrument



Aug. 26, 1930. H. a. ELDER PLOTTING INSTRUMENT Filed July 1., 1929Patented Aug. 26, 19 30 R PE T B-i i EBLbFi nl ltw -kw siiI E, o

iiimri iiie'msivimuri l i ilicatio i, filed'flfulv 1;;1929 1 Serial jug- $15,930:;

' Infth'e plotting ofi'topogr-aphic surveynotes and obser.vations', twomethods are; at present principally in fuse. The first of theses twoimethods is: the so-calledoalidade-plane table 5 method. In this'method acombination sur veying-plottingr instrument, oralidade, is;

movable over a plane-table, or, a levelled. plottingoitablecarnyingtlies'chart'01: map on which plot. 1111 "addition surveysmade by this method: are at: best'ailess iacourateithan those" madebyother methods; and no angleslare recorded, andihence no rco-iidofthelocation g9 ofthepoints, so. that iflthe' drawingsxshouldv be lost, thesurvey would have-to beinadeax Second: time; These Landz' niany otherobj ectionstend to i make this 2 methodof plotting unsatisfae-tory ;inpractice.

, 'oftenr so distorted or rexaggerated "as" torbeof little valueiwtheone plotting the map.'

Itis'an' object [of this invention toj-ovr.v come. the: difficulties in?the above rnentioned: plotting Tniethods, son1e ioffwhi'ch'f have} been'1 v referred-to; by providing; a plotting i'nstrue mentiad'apteditorbe; carried into the field; and r on with 'thefstadiaL- 1 p Journalled;inthe-i-ner end ofzthexarmQ and; rat the centen .ofsthe protractorscale/Lise there used incon-nect Anoth'er: ob' ect oftheinvention is@555:

maybe used either in the field or "in the draft:- ing. room .and.whiolilwiillfmaterially facilitate the plotting of topographicsurveynotes and observations. I o L g V In carrying my inventionfinto effect Ipro-' o videa heavy base member vvith'alprotractor g An alternativeiktoithe alidadesplaneirtable method is. the plotting in thedraftingf room"with ordinary-plotting instruments," of notes andaobservations taken: bythe estadia-transit;

, method which has-,'-- among others, the dis-1: 9 advantage thatcharacteristic features of the? ground sui'veyed -x-must 'b'efdrawn" infrom hastily made sketches and notes takeninthe, field, and thesehastily drawni'sketchesarej jecting, inward ort-infay-bea, continuousweb;

vide aportable plotting iinstrument which I .7

'seou'red thejarm f4,-,thez0t1ter. endof which 95 pivotallivinountedsoaleiarm vernier,'-wheliebyalarge numbjerof observe i tions maybejjplotted from {the {Pivotedi scale armfafter afbasejlinehasbeen=-stfilblished and: the pjrotractor OrientedEWith:respectfto, 55;

The various features "whichI believe toabe i novel and patentableareset-forth withlpar ticfularity: in thejappended c'laims fbut;forr=amorercomplete understanding: of. .tl'ieinye tionwreference ishadit'o-the following descri-p tion-,Htaken= in-connection;withvthedrawing; v in-iwhicili-Fig. 1 isaper'spectiveoview of imy I improved:plotting-instnument; Fig; 2 ,iiS';

enlarged; section taken along thelineAAu5i of Fig. 1 ;,-Fig. 3 is an,en-la rg'ed View;in per- I I spectiwe of the extreme and: of;the-scaleating, and-Figil isf'a section through thesc'afle arm;and'r'scale at'the pin 11.5 31 iMy plotting instrument comprises aibasem; en-lw vvhich is 1 marked a protracwr? allas u f ra edt ;Thisis aemayj l'gradu ld into ha d g ees a i lini'a-y Con ain w rows-'ofzscale-markings such as 05:,18) I and.

1809-3609 though such scale markilig'formsv'f no pa o y, i vention, anda y scale welli known in thearhmayibeusedf Extending;

radially-inward: from that ;p'art, ofi-the base a upon whichiisniarkedthe ppotnactorfs caleisf" e ppor ng member 2,--which ,i ias QWILFD-I isanarmintegrally connectediftd theres oi? the base andyforiningoazpa nt thereot b I which-may eonsist of a series; 0 t; afrmfsaproir.

This supporting. memberpmaysalsofl'be coilnectedi-gtotheirestofi thebaseu ibylmean s ofar I capscrewsorsdther-wellknown meansrather thanbeing formed-integrally Withitg; it ,only

carries :a, one mi-nutee verni'er figzadarpted, tog; cooperate-withthenprotnaotoi scale, .so that o ngles may; be rsetiiby; atheginstrument 1' ,tQS th n rest-minute g g Y v rn w mha pnw mo.

tractor scale, the vernier is provided with an extending tongue (notshown) which engages a groove 8 in the edge of the protractor sca e.

On the lower end of the shaft 3 is secured the scale arm 6. As shownmore clearly in Fig. 2, the pointer 4 and scale arm 6 are rigidlyconnected by a dowel pin 16 and rotate as a unit with the shaft 3. Thelower end of the shaft 3 terminates in a pin point for centering theinstrument. Obviously, any other form of pivotal arrangement of thescale arm and pointer with respect to the base member 1 might besubstituted for that specifically shown and described above withoutdeparting from the scope of my invention, the preferred embodiment beingdescribed as required by the patent statutes. The scale arm 6 isprovided with a doveg tailed groove into which may be fitted any of anumber of difierent scales 7, each provided with a dovetailed tongue 9adapted to slide in said slot. The scale arm 6 is so mounted that theedge of the scale 7 is in analignment with the center of the shaft 3 andthe zero of the vernier 5, while the bottom of the scale arm 6 and scale7 is in the plane of the base member 1, so that normally the scale arm 6and scale 7 rest on the surface so. of the paper.

The scale which is to be used is inserted at the extreme end of thescale arm 6 and when it has been inserted the full length, a smallspring catch 10 snaps a pin 11, fitted Ni into the scale arm, into ahole 12 in the scale 7 when the scale has reached its exact position.This is shown more clearly in Figs.

3 and 4. If additional scale length is desired, it may be had byreleasing catch 10 n and pulling out the scale 7 until the catch 10snaps the pin 11 into another hole 12 in the scale. Any number of theseholes 12 may be provided at any desired intervals, but I find that asingle additional hole near the center of the scale, which is preferably10 inches in length, is most satisfactory for ordinary requirements. Thescale may be marked with a second row of figures 13 to take care of thisextended position of the scale.

In order to insure that the base 1 will not move with respect to thepaper after it has been once set up, I provide the pins 14- whichoperate in vertical grooves in the base member and are held in place byspring wash ers. In order to allow the scale member 6 to swing through afull 180, the base memher 1 is cut away at 15, beneath the protractorscale at to allow the scale member to swing underneath. r I 7 coInoperating m improved plotting instrument, the pin in t e axis shaft isstuck in the point on the drawing paper representing the stationoccupied by the transit.

C 1 edge of the scaleliesagainst the 360 end of The scale arm'is thenswung around until the the protractor and the entire instrument thenrotated about the pin until the edge of the scale lies along the linerepresenting that from which the angles are turned with the transit. Thescale arm is then turned until the reading on the protractor and verniercorresponds to the angle as read with the transit, and the distance canthen be readily scaled and pointed oif on the paper. When the pointswithin 180 have been so plotted, the back of the scale arm is placedagainst the cut away portion of the protractor and the entire instrumentrotated about the axis pin until the edge of the scale lies along theline representing that from which the angles are turned with thetransit, and the plotting continued on up to 360. All turned angles canbe read directly with the instrument and, if the survey has been madewith reference to azimuths, the instrument can be oriented on the southpoint and all azimuths read directly.

What I claim anddesireto secure by Letters Patent of the United Statesis:

1. A plotting instrument comprising an arcuate protractor scale providedwith an inwardly extending radial arm in the inner end of which isjournaled a shaft, the axis of which coincides with the axis of theprotractor, a second arm secured to said shaft, one end of which secondarm is provided with a vernier adapted to cooperate with saidprotractor, the other endof. which forms a scale arm, the edge of saidscale being aligned with the axis of said instrument and the zero ofsaidvernier. i v

2. A plotting instrument comprising an arcuate protractor scale providedwith a radially inwardly extending supporting member in which ispivotally mounted, intermediate its ends, an'arm, the axis of the pivotcoinciding with the axis of the protractor, one end of said arm forminga linear scale arm and the other end being provided with a vernieradapted to cooperate with said protractor and engaging means betweensaid protractor and said vernier for insuring accurate registration.

3. A plotting instrument comprising an arcuate protractor scale providedwith a radially inwardly extending supporting member in which ispivotally mounted, intermediate its ends, an arm, the axis of the pivotcoinciding with the axis of the protractor, one end of saidarm'forming alinear scale arm and the other end being provided with a vernier adaptedto cooperate with said protractor, said vernier arm being provided withan extending tongue adapted tobe engaged by an arcuate slot in theprotractor scale.

HUBERT B. ELDER.

